Chapter 3. Major Updates

This section lists all major updates, enhancements, and new features introduced in this release of Red Hat Ceph Storage.

New ways to identify client versions

This update adds the following features that help with identifying client versions to determine which clients use an old version of Red Hat Ceph Storage.

The ceph osd set-require-min-compat-client command adds the ability to set a minimum required release for clients to prevent new connections from older clients. By default it is set to jewel. To view its value, use the ceph osd dump command.

The ceph features command that reports the total number of clients and daemons and their features and releases.

If the debugging level for Monitors is set to 10 (debug mon = 10), addresses and features of connecting and disconnecting clients are logged to log file on a local file system.

A new --pg-num option for the osdmaptool utility

The osdmaptool utility now includes the --pg-num option that can be used with the --test-map-pgs option. This allows the user to test placement policies with a different number of placement groups (PGs) than are in the OSD map.

Option to add a limit on RBD snapshots

A new option to set a limit on the number of snapshots on a RADOS Block Device (RBD) image is now supported. Use the option snap limit --limit with the rbd command to set the limit.

Ansible now supports removing Monitors and OSDs

You can use the ceph-ansible utility to remove Monitors and OSDs from a Ceph cluster. For details, see the Removing Monitors with Ansible and Removing OSDs with Ansible sections in the Red Hat Ceph Storage 3 Administration Guide. The same procedures apply also for removing Monitors and OSDs from a containerized Ceph cluster.

The iSCSI gateway is now fully supported

Red Hat Ceph Storage 3.0 adds full support for the iSCSI gateway. These iSCSI initiators are supported:

The rbd export-diff and rbd import-diff commands now support parallelism

The rbd export-diff and rbd import-diff commands have been improved to being capable of fully parallel operations. As a result, the commands now benefit from concurrency across the cluster. The commands are executed in parallel by default. To configure the amount of parallelism, use the --rbd-concurrent-management-ops <number> option when using the commands.

Support for deploying logical volumes as OSDs

A new utility, ceph-volume, is now supported. The utility enables deployment of logical volumes as OSDs on Red Hat Enterprise Linux. For details, see the Using the ceph-volume Utility to Deploy OSDs chapter in the Block Device Guide for Red Hat Ceph Storage. Note that ceph-volume does not support deploying logical volumes as OSDs in containers. In addition, ceph-volume is not tested on Ubuntu 16.04.03.

On a CephFS with only one data pool, the ceph df command shows characteristics of that pool

On Ceph File Systems that contain only one data pool, the ceph df command shows results that reflect the file storage spaces used and available in that data pool. This new functionality is available for FUSE clients only for now and will be available for kernel clients in a future release of Red Hat Enterprise Linux.

Promoting and demoting all images in a pool at once

You can now promote or demote all images in a pool at the same time by using the following commands:

rbd mirror pool promote <pool>
rbd mirror pool demote <pool>

This is especially useful in an event of a failover, when all non-primary images must be promoted to primary ones.

Ansible now automatically sets online repositories for Ubuntu

This update automates the process of setting up online repositories for Red Hat Ceph Storage on Ubuntu nodes. To set up the repositories, set the following parameters in the all.yml file located in the /usr/share/ceph-ansible/group_vars/ directory:

With this update, the OSD administration socket supports the compact command. A large number of omap create and delete operations can cause the normal compaction of the levelDB database during those operations to be too slow to keep up with the workload. As a result, levelDB can grow very large and inhibit performance. The compact command compacts the omap database (levelDB or RocksDB) to a smaller size to provide more consistent performance.

Installing NFS Ganesha by using Ansible is supported

You can now install the NFS Ganesha interface by using the ceph-ansible playbook. For additional details, see the all.yml and nfss.yml file in the /usr/share/ceph-ansible/ directory on the Ansible administration node.

RocksDB now replaces levelDB

This update changes the default back end for the omap database from the levelDB to the RocksDB database. RocksDB uses the multi-threading mechanism in compaction so that it better handles the situation when the omap directories become very large (more than 40 G). LevelDB compaction takes a lot of time in such a situation and causes OSDs to time out.

Simplified creation of CephFS client keyring

A new command, ceph fs authorize, is now supported. The command simplifies creation of cephx capabilities for a Ceph File System (CephFS) client user. For example, to grant the client.1 user read and write access to MDS nodes and read access to Monitor and OSD nodes on a Ceph File System named cephfs:

# ceph fs authorize cephfs client.1 rw r

Use this command only when creating new users. It is not possible to modify existing users with ceph fs authorize.

Granting access to Ceph Block Device images has been simplified

The ceph auth get-or-create command now supports two profiles, rbd and rbd-read-only. When using these profiles, cephx capabilities are created automatically without the need to specify them directly. For example, to create a client.1 user with required capabilities for Monitors and OSDs:

OSDs support the rbd and rbd-read-only profiles. Monitors support only the rbd profile.

MDS cache limits can be configured in bytes

New configuration options are now supported that enable configuring Metadata Server (MDS) cache limits to be configured in bytes, not only in inodes count. For details, see the Understanding MDS Cache Size Limits section in the Ceph File System Guide for Red Hat Ceph Storage 3. Note that limiting the MDS cache by the inodes count is now deprecated.

Improvements in the cluster log

The cluster log has been improved. Certain unnecessary messages, such as audit log, PGMap 5 second, or print on every osdmap epoch, have been removed. Other messages were improved to use a more human-readable format. Also, a message is not logged when health checks fail. In addition, a new command, log last, is now supported. The command shows the recent log messages.

Ceph’s built-in health checks have been refactored to enable more robust integration with external alerting systems. For each condition that is checked, there is now a unique status code, for example PG_AVAILABILITY.

Note

Any external script that was relying on the JSON syntax of the ceph status or ceph health command output must be updated for the new format. To ease migration, set the mon_health_preluminous_compat parameter to True on Monitors to instruct ceph status and ceph health to generate old-style health output in addition to the new output.

Deleting images and snapshots from full clusters is now easier

When a cluster reaches its full_ratio, the following commands can be used to remove Ceph Block Device images and snapshots:

rbd remove

rbd snap rm

rbd snap unprotect

rbd snap purge

The Ceph Object Gateway now supports NFSv3 protocol

The Ceph Object Gateway now provides the ability to export Simple Storage Service (S3) object namespaces by using NFS version 3 alongside the existing NFS version 4. For details, see the Exporting the Namespace to NFS-Ganesha section of the Red Hat Ceph Storage 3 Object Gateway Guide for Red Hat Enterprise Linux.

Support for Simple Storage Service (S3) Bucket Policy has been added. Note that the support has the following limitations:

Identity and Access Management (IAM) for users and groups is not supported

String interpolation is not supported

Only a subset of condition keys is supported

For details see the Bucket Policies section in the Developer Guide for Red Hat Ceph Storage 3.

nfs-ganesha rebased to 2.5

The nfs-ganesha package has been upgraded to upstream version 2.5, which provides a number of bug fixes and enhancements over the previous version.

NFSv4 recovery state data can be stored in Ceph RADOS

NFS version 4 (NFSv4) recovery state data such as, clientids, can now be stored in Ceph RADOS objects. This change increases the resilience of clustered NFS servers exposing Ceph storage resources.

New "radosgw-admin user list" command

Previously, the command that listed users and subusers required the user’s uid as an input. This approach required extra commands. This release introduces the radosgw-admin user list command, which lists all users and subusers without requiring any uids.

The Ceph Object Gateway now supports the Amazon Simple Storage Service (S3) server-side encryption. For details, see the S3 API Server-side Encryption section in the Developer Guide for Red Hat Ceph Storage 3.

Support for the Red Hat Ceph Storage Dashboard

The Red Hat Ceph Storage Dashboard provides a monitoring dashboard for Ceph clusters to visualize the cluster state. The dashboard is accessible from a web browser and provides a number of metrics and graphs about the state of the cluster, Monitors, OSDs, Pools, or network.

The async messenger is used by default instead of the simple one. For details see the Messaging and Async Messenger Settings section in the Configuration Guide for Red Hat Ceph Storage 3.

Support for dynamic bucket resharding

The Ceph Object Gateway now supports the rgw_dynamic_resharding parameter. The process for dynamic bucket resharding periodically checks all the Ceph Object Gateway buckets and detects buckets that require resharding. If a bucket has grown larger than specified by the rgw_max_objs_per_shard parameter, the Ceph Object Gateway reshards the bucket dynamically in the background. For details, see the Dynamic Bucket Index Resharding in RHCS 3 section in the Object Gateway Guide for Red Hat Enterprise Linux.

Note that dynamic bucket resharding is disabled in multi-site configuration.

The Ceph File System is now fully supported

The Ceph File System (CephFS) is a file system compatible with POSIX standards that provides a file access to a Ceph Storage Cluster. With this new version, CephFS is now fully supported. For details about CephFS, see the Ceph File System Guide for Red Hat Ceph Storage 3.

Scrubbing is blocked for any PG if the primary or any replica OSDs are recovering

The osd_scrub_during_recovery parameter now defaults to false, so that when an OSD is recovering, the scrubbing process is not initialized on it. Previously, osd_scrub_during_recovery was set to true by default allowing scrubbing and recovery to run simultaneously. In addition, in previous releases if the user set osd_scrub_during_recovery to false, only the primary OSD was checked for recovery activity.

A new ceph-medic utility

A new utility, ceph-medic, is now available and fully supported. The utility detects common issues with a Ceph Storage Cluster that prevents the cluster from functioning properly. For details, see the Installing and Using ceph-medic to Diagnose a Ceph Storage Cluster chapter in the Troubleshooting Guide for Red Hat Ceph Storage 3.

Colocation of containerized Ceph daemons

With this release, you can colocate specific containerized Ceph daemons with OSD daemons on the same node. This approach significantly improves total cost of ownership (TCO) at small scale, reduces the minimum configuration from six nodes to three, makes upgrading more convenient, and provides better resource isolation. Also, each daemon has system resources reserved to avoid the "noisy neighbor" effect.

Ceph Manager (ceph-mgr) is a new daemon that takes over some of the Monitor’s workload and introduces an interface for optional Python modules. Administrators must deploy at least two ceph-mgr daemons, or more typically, one ceph-mgr daemon on each node where they run a ceph-mon daemon. For details, see the Installation Guide for Red Hat Enterprise Linux or Ubuntu.

Support for the RESTful plug-in

RESTful is a plug-in for the ceph-mgr daemon that provides an API for interacting with Ceph clusters.

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